The Earth’s surface thus receives energy from two sources: the sun & the atmosphere. As a result the Earth’s surface is 33C warmer than it would be without an atmosphere. Greenhouse gases are transparent to shortwave but absorb longwave radiation. In this lecture, briefly focus on How is energy distributed to the earth’s surface; What are greenhouse gases and the greenhouse effect; Impact of an increase in atmospheric CO2 on greenhouse effect and Relationship between the greenhouse effect and global warming.